A probe head of this kind is, for example, disclosed in U.S. Pat. No. 4,963,728. The probe head described there has also a collision protective device. This collision protective device comprises a yieldable kink joint in the measuring arm of the coordinate measuring apparatus by means of which the entire probe head is suspended, that is, when a collision of the probe head with the workpiece takes place, the entire probe head is deflected out of its calibrated zero position including the imaging optics having a beam path which is tilted thereby. When the collision situation is removed, the probe head again returns to the zero position fixed by the yieldable kink joint but not with complete precision. Accordingly, and if a highly precise measuring value is wanted, the alignment of the optical probe head must be newly calibrated after a collision. This means a time delay during which the machine is not available for measuring tasks.